An 82-year-old woman was admitted to our emergency department in hemodynamically stable condition, 12h after the beginning of severe retrosternal chest pain of 1h duration, not influenced by changes in body position, nor aggravated by breathing and no more repeated. The ECG showed a typical pattern of acute pericarditis with diffuse concave upward ST-segment elevation >1 mm. Cardiac troponin levels, 12h after chest pain, were in the normal range, excluding the diagnosis of acute coronary syndrome. Chest X-ray displayed significant mediastinal enlargement. Transthoracic echocardiography documented mild anterior pericardial effusion (10 mm) and severe aneurysmal dilatation of the ascending aorta (antero-posterior diameter of 7 cm, measured 5 cm above the aortic valve plane) with significant wall thickening and no evidence of intimal flap. In addition, both left and right ventricles showed normal morphology and systolic function; pulmonary artery systolic pressure was 28 mmHg. Transesophageal echocardiography confirmed the significant dilatation of the ascending aorta, with a typical pattern of aortic penetrating ulcer (observed 5 cm above the aortic valve plane) associated with an intramural hematoma of the anterior wall, extended from the level of the sino-tubular junction to 9 cm above the aortic valve plane (acute aortic syndrome, Svensson type II). A diagnosis of acute aortic syndrome was made and, considering the risk for acute aortic dissection or aortic rupture, the patient was quickly transferred to the nearest Cardiac Surgery Center. Computed tomography confirmed the echocardiographic findings and the patient underwent replacement of the ascending aorta with a tubular prosthesis. The present case underlines the great utility of portable echocardiography in the emergency department, for the clinical evaluation of patients with different patterns of chest pain and, particularly, in the differential diagnosis of acute aortic syndromes.